In traditional Ethernet (802.3 10BASE5) and Cheapernet (802.3 10BASE2) a coaxial cable provides the linear bus to which all nodes are connected. Signalling is accomplished using a current synch technique with a center conductor used for the signal and a shield used as a ground reference. Twisted pair Ethernet (802.3 10BASE-T) utilizes standard voice grade telephone cable, employing separate transmit and receive pairs. The system uses a star topology. At the center of a star is a repeater. The repeater performs signal amplitude and timing restoration. It takes the incoming bitstream and repeats it to all the ports connected to it. In this sense the repeater acts as a logical coaxial cable so that any node connected to the network will see another node's transmission. Differential signalling is employed with one pair acting as the transmit path and the other pair acting as the receive path.
While repeaters are used in traditionally wired coaxial Ethernet as a means to extend the networks physical distance limit, in the IEEE 802.3 10BASE-T, the Standard mandates the use of a repeater to actually provide the connectivity function if more than two nodes are required. Although the physical signalling on the cabling differs, the functionality of the repeater is identical in either coaxial or twisted pair networks as is the frame or packet format that is used to pass messages between the participating nodes on the network.
The drawing of FIG. 1 shows a representative ethernet packet. Each packet comprises a series of 8-bit bytes of digital information. Each packet is preceded by a seven byte preamble composed of alternating 1s and 0s. The preamble is followed by a one byte long start frame delimiter (SFD) which presents the following eight bit sequence: 10101011. After the SFD, follows a packet that can vary in length from 64 to 1518 bytes. In particular, six bytes (48 bits) of destination address immediately follow the preamble. The destination address designates the intended destination of the packet. After the destination address, follow six bytes of source address which designate the source of the packet. After that, there are two bytes that designate the packet length. Then follow between 46 and 1500 bytes of data. Finally, there are four bytes which constitute the frame checking sequence (FCS) for checking errors.
Since all packets that are transmitted between stations must pass through repeaters, the repeater is the ideal place in which to gather network statistics. These statistics are called attributes.
A media access controller which disassemble the packet performs address checking, error detection, etc. placed within the repeater will allow network statistics to be gathered at the repeater.
The IEEE repeater management standard 802.3K requires attributes related to the packet to be stored in 32 bit counters. The gathering and storing of these attributes can be implemented in hardware or software. A software implementation processor would require significant processor overhead in the operation of the repeater. Hence, for efficiency reasons it is important to implement the statistic gathering and storing in hardware. However, to implement all the attributes as 32 bit counters would not be cost effective because the counters would occupy a significant amount of silicon.
Hence, what is needed is a system for implementing the 32 bit counter to store attributes that is a cost effective solution in accordance with the standard. What is also needed are counters for storing attributes that occupy a minimum amount of space on an integrated circuit. Finally, what is needed are 32 bit counters that are in conformance with the IEEE 802.3K standard. The present invention meets these needs.